Automatic measuring and control apparatus for forming sheet material



Nov. 26, 1968 A. E. BEECHER AUTOMATIC MEASURING AND CQNTROL APPARATUS FOR FORMING SHEET MATERIAL Filed June 14, 1965 2 Sheets-Sheet l ZQUQ wujm INVENTOR.

(Zr/m1, M 17 W QTTORNEVS Nov. 26, 1968 A. E. BEECHER 3,413,192

AUTOMATIC MEASURING AND CONTROL APPARATUS FOR FORMING SHEET MATERIAL Filed June 14, 1965 2 Sheets-Sheet 2 a A A g1 l x J L AAAAA vvvvv United States Patent 3,413,192 AUTQMATKC MEASURING AND CONTROL APPA- RATUS FOR FORIVHNG SHEET MATERIAL Alfred E. Beecher, Tacoma, Wash, assignor to St. Regis Paper Company, New York, N.Y., a corporation of New York Filed June 14, 1965, Ser. No. 463,487 13 Claims. (Cl. 162259) This invention pertains to control apparatus for controlling a selected property of continuously formed or fed sheet material, and pertains more especially to apparatus for automatically controlling a selected property of the sheet material widthwise thereof as it is being formed or continuously fed, such as the basis weight or moisture content in the case of paper, or the sheet thickness in the case of resinous sheetstock and the like.

In the continuous manufacture of various sheet-like products of the character aforesaid, it is important to obtain the highest possible degree of uniformity of significant properties. In practice, properties tend to vary from place to place in such sheets, both in the direction of manufacture (machine direction) and across the width of the sheet (cross machine direction). The control apparatus of the present invention relates to the regulation of uniformity in the cross machine direction. It is applicable to all cases in which the cross machine variations from uniformity of a property can be controlled by a plurality of like adjusting mechanisms arrayed across the machine.

It is not necessary for effecting such control to know in advance the manner in which adjustments of these mechanisms affect the profile of variation from uniformity of the property. It is only necessary that the disturbances or upsets to the cross machine profile of the property be such that relatively abrupt changes tend to occur infrequently and that continuous drift from a given adjustment tends to occur slowly in time as compared with the dynamics of the cross machine characteristics of the manufacturing machine, and as compared to any time delay which may exist between the positions of adjustment and the positions of measurement. Thus such control systems can properly be called self adaptive or learning systems.

The forming of a paper web on a Fourdrinier machine to obtain uniform basis weight of the paper in the cross machine direction by adjustments of the plurality of slice screws on the headbox slice is an example of this class of control problem. This problem is of immediate and major concern to the paper industry; and the control system of the present invention will be described in its preferred embodiment with reference thereto.

In its more generic aspects, however, the control apparatus of the invention is generally applicable to machines for forming a flowable material into sheet, as for example, by passage through a slot-like aperture which defines the thickness and width of the sheet at the point of formation, or to apparatus for modifying a property thereof, such as the moisture content, etc. For controlling a selected property of the sheet widthwise thereof when formed, for example, by means of a slot-like aperture, the slot aperture is made variably adjustable along its length by adjusting mechanisms controlling contiguous portions thereof successively. These mechanisms are in accordance with the invention, preferably controlled directly or indirectly as explained below, by servo-integrators each consisting of a servo-operational amplifier having its output connected to a servo-motor the shaft of which mounts a tachometer which feeds back to the amplifier input. In other applications of the invention as for example in controlling the moisture content of paper sheetstock, the adjusting mechanisms would be arranged Patented Nov. 26, 1968 to actuate the control valves of a series of spray nozzles under control of the servo-integrators. For appropriately actuating the servo-integrators, gauge measurin and scanning means is provided which measures the selected property to be controlled widthwise of the sheetstock, such as basis weight, thickness, moisture content, etc., and produces an electrical signal or signals, proportional thereto, or to variations thereof from the widthwise average value, which signal or signals is or are fed to the input of the servo-integrators for appropriately actuating the slot aperture or other adjusting mechanisms to maintain uniformity of the property measured across the sheet.

In order that the control apparatus of the invention shall provide incremental or decrcmental adjustments of the adjusting mechanisms with respect to the average or alternatively the minimum of the settings of all of them widthwise of the sheetstock, a signal equal to the average or alternatively the minimum setting of all of the servointegrators is also impressed on the inputs there-to, thus to minimize required incremental or decremental adjustments of the individual adjusting mechanisms on each. For basis weight or thickness control of the sheets-took the average setting is employed whereas for moisture control the minimum setting is required. Also in order further to minimize the extent of incremental or decremental adjustments of the individual adjusting mechanisms on each scan, there is also impressed on each servo-integrator, two additional signals respectively proportional to the preceding and succeeding servo-integrators in the direction of scan. This imparts a smooth-flowing actuation of the adjusting mechanisms as the scanning proceeds and eliminates large and abrupt adjustments thereof from actuator to actuator.

As employed in a Fourdrinier paper machine for controlling the slice lip adjustment thereof, the motor shafts of the servo-integrators are in accordance with one embodiment of the invention, directly linked mechanically as through appropriate gearing, to adjusting mechanisms interposed at spaced intervals between the slice lip and the slice beam of the machine, thereby directly to adjust successive slice lip segments in accordance with actuations of the successive servo-integrators under control of the scanning gauge signal and other signals above-mentioned. This construction although fully automatic in operation, lacks the flexibility of remote manual adjustments for the individual slice lip segments during operation, which is often desirable for overriding the automatic regulation.

This feature is incorporated in accordance with a preferred embodiment of the invention by interposing servomotor positioners or actuators between the servo-integrators and the slice lip adjusting mechanisms in accordance with an arrangement wherein the motor shafts of the servo-motor positioners are mechanically linked to the adjusting mechanisms for actuating the same, and wherein the electrical inputs to servo-motor positioners are electrically connected to potentiometers or equivalent units which are variably adjusted in accordance with the set- -tings of the servo-integrator motors respectively. This is quite simply accomplished by mounting the variable arm of each potentiometer on the motor shaft of the associated servo-integrator.

Each servo-motor positioner preferably comprises a servo-input amplifier to the output of which the servomotor of the positioners is connected, and mounted on the positioner motor shaft is the adjustable arm of a potentiometer energized from a direct current source which is connected to the amplifier input to provide a feedback connection thereto. In this way each servo-positioner or actuator is positioned in accordance with the setting of the motor shaft and associated potentiometer of the servointegrator electrically connected thereto. Thus the servopositioners follow any and all movements of their associated servo-integrators, which are in turn actuated in accordance with the gauge signals and other signals impressed thereon as above-described. Likewise the slice lip adjusting mechanisms are adjusted in accordance with the actuation of the servo-positioners.

Advantages of this arrangement are that the servointegrators may be mounted in a console remote from the Fourdrinier machine headbox, as for example in the operators console, from which the motor shafts of the servo-integrators may be arranged to project and be provided with manually adjustable control knobs for manually adjusting each servo-integrator and thereby each servopositioner and the associated slice lip adjusting mechanism. The operator can thus override the automatic operation of the control system at any time by effecting such manual adjustment as may become necessary from time to time during operation of the paper machine. This overriding mode of manual control eliminates transients that would otherwise be encountered in switching from automatic to manual operation and vice-versa.

The preferred embodiment of the invention as thus describd provides adequate flexibility and reliability of operation in that three modes of control of uniformity of cross machine basis weight profile are available to the operator; namely, a fully automatic mode in which the control system obtains and maintains the uniformity of cross machine basis weight profile; a remote manual adjustment mode in which the operator can adjust the positions of each slice screw from a console while he is remote from the slice lip of the machine, and in proximity with and in response to a chart recorder which repeatedly displays the cross machine basis weight profile of the sheet which is being produced; and a local manual mode in which the operator can adjust the position of each slice screw by ascending the bridge above the slice and manually adjusting the slice screws. This would be required in the event of loss of electrical power to the slice screw actuators or electrical failure of any of these.

With either embodiment of the invention as above described, a switching mechanism is actuated in synchronism with the scanning gauge traverse, for successively connecting the power input supply to the servo-integrator amplifiers, as the scanning gauge moves in alignment with successive slice lip segments controlled by the successive servo-integrators, or alternatively in alignment with any desired group of contiguous such segments controlled by a corresponding group of contiguously disposed servointegrators, as described in detail hereinafter.

A signal proportional to the average or alternatively the minimum setting of all of the servo-integrators is'obtained by incorporating in the control apparatus, an averaging or summing amplifier to the input of which the variable arm of the servo-integrator potentiometers are connected in parallel, the output of this amplifier being in turn connected to the input of all of the servo-integrator amplifiers.

Advantages of the present invention which are believed to be original and unique therewith are the following:

(1) Knowledge of a relationship which defines the cross machine distribution of stock from the slice onto the forming wire is not required. Stock which is delivered through any slice segment may be presumed to distribute over adjacent segments of the wire as well as over its associated segment. Descriptions of previous devices have claimed the need for assuming that the weights of the individual cross machine paper web segments are determined almost entirely by the opening of their corresponding slice segments. (2) The integrated control signal includes negative feedback of the average slice opening to eliminate the virtually impossible requirement that the integrated basis weight error delivered to and distributed among the slice openings be completely without long term bias. In all real systems this bias will be inherent in both the development of the basis weight error signal and in its integration by the control system. Systems which do not in some manner feed back some indication of average slice opening will eventually either totally open or totally close to their limits. (3) Feedback means are included to select the most desirable solution when a multiplicity of solutions to the self-adaptive control problem exists. (4) The control system is equipped to vary the width of the paper web segment which is associated with or corresponds to a slice opening segment. For example, a Fourdrinier with 40 slice segments may operate each slice segment from a paper web scan segment in line with it, which is one-tenth of the paper machine Width which in this example is four slice segments wide. (5) The control system is operative during both backward and forward scans of the gauge where the gauge scans by reciprocative movement widthwise of the sheet. Also corrections can be made on every scan regardless of the transit time from the Fourdrinier to the gauge. (6) Means are included to operate the slice adjustments at the edges of the untrimmed paper web when trimming prohibits subsequent scanning by a gauge. (7) Analog integration for each slice position requiring such is accomplished by adding a feedback tachometer to an already essential motor-amplifier combination. This allows a large reduction in computing apparatus. (8) Integrator drift which often arises with integrators operating over long time intervals is minimized by turning them off when not in use. (9) The three mode control system uses servo-positioners on the slice lip driven by positioning devices on the operators console. This allows switching between automatic and remote adjustment without abrupt transients. (10) In times of extreme upset, and operator can override the automatic mode without switching to remote manual adjustment. (11) A wholly manual mode is available.

In the annexed drawings, FIG. 1 illustrates partly in perspective view and partly in diagrammatic showing, a preferred embodiment of the actuator portion of the control system of the invention as employed in a paper-making machine for controlling the slice lip adjustment thereof along its length and thereby the basis weight of the paper being produced across its width. FIG. 2 is an enlarged fragmentary view in elevation and partly in section, showing the mechanical details of one of the slice lip actuators for providing automatic adjustment of a portion thereof. FIG. 3 illustrates diagrammatically the electromechanical control circuits and linkages for automatically controlling the slice lip actuators of FIG. 1. FIG. 4 illustrates a switching arrangement forming an integral portion of the control system.

Referring to the FIG. 1 drawing, there is shown in general scheme at 10, a Fourdrinier paper-making machine, including the headbox 11, the front wall of which is broken away, as at 12, to show the slice lip 13 of flexible sheet metal, secured along its upper edge to a support above the slice lip opening 14, the lower edge of the slice lip being free for varying the slice lip opening, and being vertically adjustable along its length by actuators, such as A A A A A spaced therealong, these actuators being mechanically linked at their lower ends to the slice lip, as at 15, and being mechanically linked at their upper ends to the slice beam 16, as at 17, the slice beam being rotatable by means of worm gearing 18 manually operated by a hand-wheel 18a, for raising or lowering the slice lip as a whole.

Referring to FIG. 2, each of the slice lip actuators, that in FIG. 2 being designated for generality as actuator A comprises a vertically expansible and contractible mechanical linkage member consisting of a housing 19, mechanically linked at its upper end to the slice beam 16 by means of a stud 20 terminating in an eyelet 21, secured by means of a pin 21a between bifurcated arms 21b, integral with and projecting outwardly from the slice beam 16. Within the the housing 19 is slidably mounted a rack member 22 from which extends a stud 23 terminating in an eyelet 24 which is secured to the slice lip 13. Meshing with the rack member 22 is a pinion 25 mounted on a shaft 26 extending to a gear train 27 which is geared to the shaft 28 of an electrical servo-motor 8;. Thus as the motor is energized in one direction of rotation or the reverse, the gear 25 will be correspondingly rotated to drive the rack up or down as the case may be and thereby contract or expand the linkage coupling between the slice lip and the slice beam, thus to provide up or down adjustment of the lower edge of the slice lip over the portion thereof controlled by any particular such linkage.

Reverting to FIG. 1, any desired number of such actuator linkages A may be provided depending on the length of the slice lip for any particular machine, only eight being illustrated in the drawing as sufficient for the purposes of explaining the operation of the control system of the invention.

In FIG. 1, the Fourdrinier machine 10 is shown in proccess of forming a continuous web of paper 30 from a water slurry of fibrous paper stock fed into the headbox, as at 31, and issuing thence through the slice lip opening slot 14, beneath the slice lip 13, and deposited in a continuous web onto the Fourdrinier wire 32, .as it passes about the breast roll 33. Most of the water is drained oif through the wire by gravity and suction as the web is conveyed therewith until the wire passes about the couch roll 34, fro-m whence the web is fed between the press rolls, 35, 36, for removal of additional moisture and compressing and bonding the web. The web is fed thence through the dryer section about dryer rolls, as at 37, in conventional fashion, from which the finished paper web issues, as at 30, and passes onto the windup reel (not shown).

As the web issues from the dryer section it passes through an elongated slot of a U bracket 41 mounting at its outer end, a basis weight measuring gauge comprising a source of nuclear radiation mounted on the lower arm of the bracket, as at 42, the radiant energy from which is directed upwardly through the paper stock onto a radiation detector, such as an ion chamber, mounted on the upper bracket arm, as at 43, and to which is connected an insulated conductor 44. A scanning beta gauge may be employed for this purpose. The radiant energy passing through the paper generates an electrical voltage or potential E which is adjusted by means of a biasing voltage or otherwise to be approximately proportional to the variation of the basis weight of the paper at the point of scanning from the widthwise average across the sheet. The signal E is impressed on the conductor 44 and utilized for slice lip control regulation as hereinafter explained. The gauge thus provided is adequately responsive in operation and thus provides a continuous measure of the basis weight and variations in basis weight of the continuously-fed paper web at the point of measurement.

Since the paper web is subject to basis weight variations transversely thereof, the gauge supporting U bracket 41 is displaceably mounted on a stationary tracking support 45, extending transversely beneath the web, and the bracket is provided with suitable means for reciprocatively driving the bracket back and forth along the tracking member, whereby the gauge progressively scans and measures the paper web basis weight transversely thereof.

As above discussed with reference to FIG. 2, each of the slice lip adjustment actuators is actuated and adjustably positioned by means of a servo-motor, that in FIG. 2 being designated S for actuator A and the same applies with reference to each of the actuators A to A inclusive, of FIG. 1, wherein there is shown only for actuator A the servo motor 8; therefor together with the electrical system which energizes this motor as shown within the rectangle Z As therein shown, the operating circuits for motor S comprise an input servo-amplifier 47 to the output of which motor 8, is connected. Associated with motor S is a potentiometer, the resistance element 48 of which is connected across a direct current power supply 49, the 7 resistance element 48 being variably tapped by a variable arm 50 mounted on the motor shaft 51. A feedback connection 52 extends from the variable arm 51 to the input of amplifier 47 as shown. The amplifier is also provided with a signal voltage input connection 52a. With the circuit connections described, motor S operates as a servopositioner and is rotated in direction and extent proportional to the polarity and magnitude of a signal voltage impressed on the input lead 52a.

Referring now to FIG. 3, signal voltage for adjustably positioning the actuators A A A A i etc., and the slice lip segments controlled thereby, are obtained from a series of potentiometers P P P P etc., individual to the actuator motors S S 8,, S etc., respectively.

Each of the potentiometers comprises a fixed arm resistance, as at 54 of potentiometer P which is variably tapped by an adjustable arm, as at 55, which latter is mounted on the shaft, as at 56, of an associated servomotor M The fixed arms of all the potentiometers P P etc., are connected in parallel electrically between a pair of conductors 57, 58, which are respectively connected to the opposite terminals of a direct current power supply source 59. The variable potentiometer arms are respectively connected to terminals F F etc., and thence respectively to the input leads of the servo-amplifiers, such as 47, of the servo-motors S S etc., in the manner shown for the connection from terminal F, of FIG. 3 over conductor 52a to the input amplifier 47 of servomotor 8, of FIG. 1.

With the arrangement described, adjustment of the servo-actuator A for example, will be determined by the setting of the servo-motor 5,, which in turn is determined by the setting of the variable "arm of potentiometer P which latter is in turn determined by the setting of the associated servo-motor M Hence the actuator A, and the setting of slice lip segment adjusted thereby, will follow any and all movements of the variable arm setting of potentiometer P which in turn will follow any and all movements of the servo-motor M And the same construction and mode of operation, of course, applies to each of the other slice lip actuators A A etc., with respect to adjustments thereof under control of their respective potentiometers P P etc., and servo control motors M1, M2, etc.

Each of the control motors M etc., and its associated potentiometer P etc., may be manually adjusted by means of a control knob mounted on the motor shaft, as at 63, for motor M Alternatively, these adjustments may be made electrically and automatically in the manner now to be described. Thus each servo-motor, such as M has associated therewith a servo-operational amplifier G the circuit connections and operation of which will be described only with reference to motor M since they are the same with reference to the remaining motors M of the series except for the terminal motors M and M as discussed below. Mounted on the shaft of motor M, is a tachometer T, which provides a feedback signal to the input of amplifier G over a connection 64. Motor M, will turn in a direction and at a rate determined by and proportional to the arithmetical sum including sign (i.e., negative voltages subtracted from plus voltages) of all voltages applied to the input of amplifier G the output of which is connected to motor M over connection 65.

Before discussing these voltages it is to be pointed out that each of the amplifiers G etc., is operative only when electrical power is supplied to the power input terminal V etc., of each.

The signal voltage E from the web basis weight measuring gauge is impressed on the inputs of all of the G amplifiers G to G inclusive, over an input connection 70, FIG. 3, which is connected to lead 44 of FIG. 1. In addition there is impressed on the inputs of all of the amplifiers G to G inclusive, over input lead 71, FIG. 3, a voltage E which is proportional to the mean or average setting of all of the servo-motors M to M inclusive, at any given instant. This voltage E is obtained by connecting the variable tapping point of each of the potentiometers P to P inclusive, to the input of an averaging amplifier L the output of which is connected over conductor 72 to conductor '71. Thus the variable tapping points on each of the potentiometers P P h P P are connected to the input of amplifier L over connections 71a, 71b; 72a; 73, 73a; 74, 74a; and 75, 75a, respectively; and similarly for each of the remaining potentiometers P. There is also impressed on the input to each of amplifiers G to G inclusive, a voltage proportional to the variable arm settings of the potentiometers P both preceding and succeeding that of the potentiometer associated with any such G amplifier. Thus for amplifier G associated with potentiometer P the variable arm setting of the preceding potentiometer P is connected to the input of amplifier G over connections 73, 76, and the setting of the succeeding potentiometer P is connected to the input of amplifier 6, over connections 75, 77.

Thus each of the amplifiers G to G has impressed on its input in addition to its tachometer voltage T:

(1) The paper web gauge measuring voltage E of such polarity as to cause the associated slice lip segment to close when the associated paper web segment is too heavy.

(2) The average voltage E from the averaging amplifier L of such polarity as to cause the slice lip segments to close if a predominance of the slice lip segments are more than half open as defined by the average.

(3) The position signal Ft'i-l-l) from the (i-l-l) potentiometer causing A, to open if A is more than half open.

(4) The position signal F(il) from the (il) potentiometer operating the same as above.

Referring to FIG. 4, there is shown a rotary switch 89 having a rotary switch arm 81. Disposed about the terminus of the switch arm 81 are arcuately and equiangularly disposed a series of stationarily-mounted reed switches R to R inclusive. The reed switches are an gularly disposed in positions corresponding to the lateral spacings of the actuators A to A inclusive, across the width of the paper web 30, so that as the web basis weight measuring gauge 42, 43, moves transversely across the paper Web during scanning, the terminus of the rotary switch arm 81 is so driven as to sweep successively past the reed switches R R as the gauge 42, 43, moves into alignment with the slice lip segments controlled by actuators A A respectively. An electromagnet 82 is affixed to the outer terminus of the switch arm 81, and is energized from an adjustable source of direct current supplied over connections 82a, so that as the rotary switch sweeps successively past the reed switches R -R they are successively actuated to the closed condition. One contact of each of the reed switches is supplied with power from a source V, while the opposite contacts are connected, respectively, to the power input leads V to V respectively, of the amplifiers G to G In this way the amplifiers G to G are successively energized during intervals that the gauge 42, 43, scans transversely across strip widths of the paper web 30 which are in alignment with the slice lip segments controlled by the actuators A to A Depending on the amount of current supplied to the electromagnet 82, the reed switches may be individually operated as the electromagnet sweeps past them, or alternatively two or more adjacent reed switches may be thus actuated on a progressive group basis, thus to actuate the actuators A singl or in contiguous groups, thereby to adjust the slice lip over shorter or longer segments thereof as desired on each sweep of the gauge. Because the integrating systems 6,, M T are never reset (except perhaps when the paper machine is down), each accomplishes a continued integration of the basis weight of its corresponding paper web segment through scan after scan of the traversing gauge, and a combination of averaging and integration during the appropriate portion of each scan.

In paper-making machines wherein the opposite lateral edges of the paper web are trimmed before the sheet passes under the traversing mass gauge 42, 43, as is almost always the case, the terminal actuator systems which are in alignment with these trimmed edges must be modified in the respects shown in FIG. 3 for the terminal actuator system G M From this it will be seen that the feedback signal which for the other servo-amplifiers is obtained from their associated tachometers, in this case is obtained from the associated potentiometer P over connection 35 and the only signals applied to the servoamplifier G are obtained from the potentiometers P and P g of the two adjacent servo-amplifiers G and G over connections 72a, 87 and 73, 88. An identically similar arrangement is employed for the terminal amplifier G at the opposite end of the series. This configuration provides a nonintegrating positioner for the motors M and M at the lateral edges of the sheet, which operate from the average error over the edge of the sheet and which is the only place where these actuators have measurable effect. It is to be understood with reference to the above that the paper machine may be so trimmed that the edge portions of the Web associated with more than one edge actuator on each side of the sheet is trimmed before the sheet passes through the scanning gauge, in which case more than one of the amplifiers at the opposite edges of the slice is arranged in the manner above described.

Referring to FIG. 3, variable resistors are interposed at various points in the electrical circuits shown, and as at 90-99, inclusive, for appropriately adjusting the various signaling voltages impressed on the servo-amplifiers, both relatively and in absolute magnitude for proper functioning of the control system. Thus for example by adjustment of the variable resistors 90 and 99 the voltage E and E as impressed on the servo-amplifiers G G etc., are adjusted in such manner that the feedback voltage E for the average slice opening is balanced in its effect against the primary property indicating signal voltage E from the scanning gauge 42, 43, which measures variations in the cross machine direction. Thereby corrections of such variations are balanced against the requirement for maintaining the average of the actuator positions close to their median setting. Also the input signals to the servo-amplifiers obtained from the potentiometers of adjacent amplifiers are so adjusted b means of the remaining resistors above-mentioned as to reduce elastic distortions of the slice lip in such manner as to balance these signal inputs against those of E and E What is claimed is:

1. Control apparatus for controlling a selected property of continuously fed sheet material, comprising: a series of actuator means disposed at intervals across the width of said sheet, said actuator means being individually adjustable for controlling said property over successive fractional widths of said sheet, scanning means for measuring said property over said fractional sheet widths and for generating electrical signals as a function thereof, separate servo-integrator means linked to each of said actuator means by respective positioner means for adjusting each of said actuator means in accordance with the actuation of the corresponding servo-integrator means, and means for impressing said electrical signals on said servo-integrator means for thereby adjusting said actuator means to minimize variations in said selected property of said sheet material.

2. Control apparatus for controlling a selected property of continuously fed sheet material, comprising: a series of servo-actuator means disposed at intervals across the width of said sheet, said servo-actuator means being individually adjustable for controlling said property over successive fractional widths of said sheet, scanning means for measuring said property over said fractional sheet widths and for generating electrical signals as a functon thereof, separate servo-integrator means linked to each of said servo-actuator means by respective means for adjusting each of said servo-actuator means in accordance with the actuation of the corresponding servo-integrator means, an averaging amplifier, means for impressing an on input of said amplifier an electrical signal proportional to the setting of each said servo-integrator means to produce in an output of said amplifier an electrical signal propertional to the average setting of all said servo-integrator means, and means for impressing on an input of each of said servo-integrator means said output signal from said averaging amplifier and also said signals from said scanning means for thereby adjusting said servo-actuator means to minimize variations of said selected property of said sheet material from a selected average value of said property widthwise thereof.

3. Control apparatus for controlling a selected property of continuously fed sheet material, comprising: a series of servo-actuator means disposed at intervals across the width of said sheet, said servo-actuator means being individually adjustable for controlling said property over successive fractional widths of said sheet, a scanning gauge and means for reciprocating the same across the width of said sheet for measuring said selected property over said sheet at each point of scanning and for generating a first electrical signal as a function thereof, separate servo-integrator means linked to each of said servoactuator means by respective means for adjusting each of said servo-actuator means in accordance with the setting of the corresponding servo-integrator means, an averaging amplifier, means for impressing on an input of said amplifier an electrical signal proportional to the setting of each said servo-integrator means to produce in an output of said amplifier a second electrical signal proportional to the average setting of all said servo-integrator means, and means for impressing said first and second signals on an input of each of said servo-integrator means for thereby adjusting said servo-actuator means to minimize variations of said selected property of said sheet material from a selected average value of said property widthwise thereof.

4. Control apparatus for controlling a selected property of continuously fed sheet material, comprising: a series of servo-actuator means disposed at intervals across the width of said sheet, said servo-actuator means being individually adjustable for controlling said property over successive fractional widths of said sheet, a scanning gauge and means for reciprocating the same across the Width of said sheet for measuring said selected property over said sheet at each point of scanning and for generating a first electrical signal as a function thereof, separate servo-integrator means linked to each of said servo-actuator means by respective means for adjusting each of said servo-actuator means in accordance with the setting of the corresponding servo-integrator means, an averaging amplifier, means for impressing on an input of said amplifier an electrical signal proportional to the setting of each said servo-integrator means to produce in an output of said amplifier a second electrical signal proportional to the average setting of all said servo-integrator means, means for impressing said first and second signals on an input of each of said servo-integrator means, and switching means operative in accordance with movement of said scanning gauge for successively energizing said separate servo-integrator means for thereby successively adjusting said corresponding servo-actuator means as said scanning gauge scans said fractional Widths successively, to thereby minimize variations of said selected property of said sheet material from a selected average value of said property widthwise of said sheet material.

5. Control apparatus for controlling a selected property of continuously fed sheet material, comprising: a series of servo-actuator means disposed at intervals across the width of said sheet, said servo-actuator means being individually adjustable for controlling said property over successive fractional Widths of said sheet, a scanning gauge and means for reciprocating the same across the Width of said sheet for measuring said selected property over said sheet at each point of scanning and for generating a first electrical signal as a function thereof, a series of separate servo-integrator means linked one to each of said servo-actuator means by respective means for adjusting each of said servo-actuator means in accordance with the setting of the corresponding servo-integrator means, an averaging amplifier, means for impressing on an input of said amplifier an electrical signal proportional to the setting of each said servo-integrator means to produce in an output of said amplifier a second electrical signal proportional to the average setting of all said servo-integrator means, means for impressing said first and second signals on an input of each of said servo-integrator means and for additionally impressing on said inputs of each servo-integrator means a third and a fourth electrical signal proportional to the setting of the servo-integrator means adjacent thereto on each side thereof in said series, and switching means operative in accordance with movement of said scanning gauge for successively energizing said separate servo-integrator means for thereby successively adjusting the corresponding actuator means controlled thereby as said scanning gauge scans said fractional strip widths successively, to thereby minimize variations of said selected property of said sheet material from a selected average value of said property widthwise of said sheet material.

6. In an apparatus for forming a flowable material into a continuous sheet of substantial Width: slot-defining means for forming said material into said sheet, said slotdefining means being variably adjustable along its length to vary the aperture of the slot defined thereby across the Width of said sheet, separate actuator means disposed at intervals along said slot-defining means and operatively coupled thereto for adjustably varying said slot aperture over corresponding contiguous portions thereof, scanning gauge means for measuring a selected property of said sheet at a plurality of points across the width of said sheet and for generating an electrical signal as a function thereof, separate servo-integrator means linked to each of said actuator means by respective means for adjusting each of said actuator means in accordance with actuation of the corresponding servo-integrator means, and means for impressing said electrical signal on said servo-integrator means for actuating the same successively to integrate said electrical signal as generated by said gauge means over corresponding successive widths of said sheet in alignment with said slot aperture portions, thereby to actuate the corresponding actuator means to adjust the respective slot aperture portions in accordance with the actuations of the corresponding servo-integrator means.

7. In an apparatus for forming a flowable material into a continuous sheet of substantial width: slot-defining means for forming said material into said sheet, said slotdefining means being variably adjustable along its length to vary the aperture of the slot defined thereby across the width of said sheet, separate servo-actuator means disposed at intervals along said slot-defining means and operatively coupled thereto for adjustably varying said slot aperture over corresponding contiguous portions thereof, a scanning gauge and means for reciprocating the same across the width of said sheet for measuring a selected property of said sheet at each point of scanning and for generating a first electrical signal as a function thereof, separate servo-integrator means linked to each of said servo-actuator means by respective means for adjusting each of said servo-actuator means in accordance with the setting of the corresponding servo-integrator means, an averaging amplifier, means for impressing on an input of said amplifier an electrical signal proportional to the setting of each said servo-integrator means to produce in an output of said amplifier a second electrical signal proportional to the average setting of all of said servo-integrator means, and means for impressing said first and second signals on an input of each of said servointegrator means for actuating the same successively to integrate said signals as said gauge scans corresponding successive widths of said sheet in alignment with said slot aperture portions, thereby to actuate the corresponding servo-actuator means to adjust the respective slot aperture portions in accordance with the resultant actuations of the corresponding servo-integrator means.

8. In an apparatus for forming a flowable material into a continuous sheet of substantial width: slot-defining means for forming said material into said sheet, said slotdefining means being variably adjustable along its length to vary the aperture of the slot defined thereby across the Width of said sheet, separate servo-actuator means disposed at intervals along said slot-defining means and operatively coupled thereto for adjustably varying said slot aperture over corresponding contiguous portions thereof, a scanning gauge and means for reciprocating the same across the width of said sheet for measuring a selected property of said sheet at each point of scanning and for generating a first electrical signal as a function thereof, separate servo-integrator means linked to each of said servo-actuator means by respective means for adjusting each of said servo-actuator means in accordance with the setting of the corresponding servo-integrator means, an averaging amplifier, means for impressing on an input of said amplifier an electrical signal proportional to the setting of each said servo-integrator means to produce in an output of said amplifier a second electrical signal proportional to the average setting of all of said servo-integrator means, switching means operative in accordance with movement of said scanning gauge for successively energizing the servo-integrator means corresponding to the servo-actuator means controlling slot aperture portions which are disposed in alignment with said scanning gauge as it moves across said sheet, and means for impressing said first and second electrical signals on an input of each said servo-integrator means thereby to adjust the slot aperture portions controlled thereby, respectively, in accordance with the resultant of said signals.

9. In an apparatus for forming a flowable material into a continuous sheet of substantial width: slot-defining means for forming said material into said sheet, said slotdefining means being variably adjustable along its length to vary the aperture of the slot defined thereby across the width of said sheet, separate servo-actuator means disposed at intervals along said slot-defining means and operatively coupled thereto for adjustably varying said slot aperture over corresponding contiguous portions thereof, a scanning gauge and means for reciprocating the same across the width of said sheet for measuring a selected property of said sheet at each point of scanning and for generating a first electrical signal as a function thereof, a series of separate servo-integrator means linked one to each of said servoactuator means by respective means for adjusting each of said servo-actuator means in accordance with the setting of the corresponding servointegrator means, an averaging amplifier, means for impressing on an input of said amplifier an electrical signal proportional to the setting of each said servo-integrator means to produce in an output of said amplifier a second electrical signal proportional to the average setting of all said servo-integrator means, means for impressing said first and second electrical signals on an input of each of said servo-integrator means and for additionally impressing on said inputs of each servo-integrator means a third and fourth electrical signal proportional to the settings of the servo-integrator means adjacent thereto on each side thereof in said series, and switching means operative in accordance with movement of said scanning gauge for successively energizing the servo-integrator means corresponding to the servo-actuator means controlling slot aperture portions which are disposed in alignment with said scanning gauge as it moves across said sheet, thereby to adjust said slot aperture portions in accordance with the resultant of said electrical signals impressed on said inputs of said servo-integrator means.

10. In an apparatus for forming a flowa'ble material into a continuous sheet of substantial width: slot-defining means for forming said material into said sheet, said slot-defining means being variably adjustable along its length to vary the aperture of the slot defined thereby across the width of said sheet, a series of separate servoactuator means disposed at intervals along said slot-defining means and operatively coupled thereto for adjustably varying said slot aperture over corresponding contiguous portions thereof, a scanning gauge and means for reciprocating the same across the width of said sheet for measuring a selected property of said sheet at each point of scanning and for generating an electrical signal as a function thereof, a plurality of separate servo-integrator means and servo-positioner means arranged in a series with the servo-positioner means at the ends of the series and the servo-integrator means in between, said series of means being linked one to each of said servo-actuator means by respective means with said servo-positioner means being linked to the servo-actuator means at the respective ends of said slot-defining means for adjusting each of said servo-actuator means in accordance with actuation of the corresponding servo-integrator means or servo-positioner means, means for impressing said signal on all of said servo-integrator means for actuating the same successively to integrate said signal as said gauge scans corresponding successive widths of said sheet in alignment with said slot aperture portions, thereby to actuate the corresponding servo-actuator means to adjust the respective slot aperture portions in accordance with the actuations of the corresponding servo-integrator means, and means for adjusting said servo-positioner means, respectively, in accordance with the settings of the thereto adjacent servo-integrator means of said series thereby to adjust the servo-actuator means and slot aperture portions corresponding to said servo-positioner means in accordance with the actuations of said servo-positioner means.

11. Control apparatus for controlling a selected property of continuously fed sheet material, comprising: a series of actuator means disposed at intervals across the width of said sheet, said actuator means being individually adjustable for controlling said property over successive fractional widths of said sheet, scanning means for measuring said property over said fractional sheet widths and for generating electrical signals as a function thereof, separate servo-integrator means coupled to each of said actuator means by respective means for adjusting each of said actuator means in accordance with the actuation of the corresponding servo-integrator means, an averaging circuit, means for impressing on an input of said averaging circuit an electrical signal proportional to the setting of each said servo-integrator means to produce in an output of said averaging circuit an electrical signal proportional to the average setting of all said servointegrator means, and means for applying to an input of each of said servo-integrator means said signals from said scanning means and, as a negative feedback signal, said output signal from said averaging circuit for thereby adjusting said actuator means to minimize variations of said selected property of said sheet material from a selected average value of said property widthwise thereof.

12. Control apparatus for controlling a selected property of continuously fed sheet material, comprising: a series of actuator means disposed at intervals across the width of said sheet, said actuator means being individually adjustable for controlling said property over successive fractional Widths of said sheet, a scanning gauge and means for reciprocating the same across the width of said sheet for measuring said selected property over said sheet at each point of scanning and for generating a first electrical signal proportional to the deviation of said property from a selected average value, a series of separate servo-integrator means linked one to each of said actuator means by respective means for adjusting each of said actuator meansin accordance with the setting of the corresponding servo-integrator means, an averaging circuit, means for applying to an input of said averaging circuit an electrical signal proportional to the setting of each of said servo-integrator means to produce in an output of said averaging circuit a second electrical signal proportional to the average setting of all of said servointegrator means, means for applying to an input of each of said servo-integrator means said first signal and a third and a fourth electrical signal proportional, respectively, to the settings of the servo-integrator means adjacent thereto on each side thereof in said series, means for additionally applying said second signal as a negative feedback signal to said inputs of said servo-integrator means, and switching means operative in accordance with movement of said scanning gauge for successively energizing said separate servo-integrator means for thereby successively adjusting the corresponding actuator means controlled thereby as said scanning gauge scans said fractional strip widths successively, to thereby minimize variations of said selected property of said sheet material from said selected average value of said property widthwise of said sheet material.

13. In an apparatus for forming a flowable material into a continuous sheet of substantial width: slot-defining means for forming said material into said sheet, said slot-defining means being variably adjustable along its length to vary the aperture of the slot defined thereby across the Width of said sheet, separate actuator means disposed at intervals along said slot-defining means and operatively coupled thereto for adjustably varying said slot aperture over corresponding contiguous portions thereof, a scanning gauge and means for reciprocating the same across the Width of said sheet for measuring a selected property of said sheet at each point of scanning and for generating a first electrical signal proportional to the deviation of said property from a selected average value, a series of separate servo-integrator means linked one to each of said actuator means by respective means for adjusting each of said actuator means in accordance with the setting of the corresponding servo-integrator means, an averaging circuit, means for applying to an input of said averaging circuit an electrical signal proportional to the setting of each of said servo-integrator means, to produce in an output of said averaging circuit a second electrical signal proportional to the averaging setting of all of said servo-integrator means, means for applying to an input of each of said servo-integrator means said first signal and a third and a fourth electrical signal proportional, respectively, to the settings of the servo-integrator means adjacent thereto on each side thereof in said series, means for additionally applying said second signal as a negative feedback signal to said inputs of said servo-integrator means, and switching means operative in accordance with movement of said scanning gauge for successively energizing the servo-integrator means corresponding to the actuator means controlling slot aperture portions which are disposed in alignment with said scanning gauge as it moves across said sheet, thereby to adjust said slot aperture portions in accordance with the resultant of said electrical signals applied to said inputs of said servo-integrator means.

References Cited UNITED STATES PATENTS 3,000,438 9/1961 Alexander l62259 3,024,404 3/1962 Ziifer l62262X S. LEON BASHORE, Primary Examiner. 

1. CONTROL APPARTUS FOR CONTROLLING A SELECTED PROPERTY OF CONTINUOUSLY FED SHEET MATERIAL, COMPRISING: A SERIES OF ACTUATOR MEANS DISPOSED AT INTERVALS ACROSS THE WIDTH OF SAID SHEET, SAID ACTUATOR MEANS BEING INDIVIDUALLY ADJUSTABLE FOR CONTROLLING SAID PROPERTY OVER SUCCESSIVE FRACTIONAL WIDTHS OF SAID SHEETS, SCANNING MEANS FOR MEASURING SAID PROPERTY OVER SAID FRACTIONAL SHEET WIDTH AND FOR GENERATING ELECTRICAL SIGNALS AS A FUNCTION THEREOF SEPARATE SERVO-INTEGRATOR MEANS LINKED TO EACH OF SAID ACTUATOR MEANS BY RESPECTIVE POSITIONER MEANS FOR ADJUSTING EACH OF SAID ACTUATOR MEANS IN ACCORDANCE WITH THE ACTUATION OF THE CORRESPONDING SERVO-INTEGRATOR MEANS, AND MEANS FOR IMPRESSING SAID ELECTRICAL SIGNALS ON SAID SERVO-INTEGRATOR MEANS FOR THEREBY ADJUSTING SAID ACTUATOR MEANS TO MINIMIZE VARIATIONS IN SAID SELECTED PROPERTY OF SAID SHEET MATERIAL. 